1. The Area Of A Trapezium.
A Trapezium is any closed shape which has two sides that are parallel and two sides that are not parallel.

2. We are now going to find a formula for the area of the trapezium:
Cut the trapezium in half:

3. Rotate the top piece and move alongside the bottom piece
What shape has been formed?
So what is the area of the trapezium?

4. Replace the numbers with letters
So to find the rule:
A(trap) = (a + b) x ½ h

5. Example 1
Calculate the area of the trapezium below :
16cm
11cm
13cm
Solution ( Using the formula).
A(trap) = ( a + b ) x ½ h
= ( ) x ½ x 13
= 27 x 6.5
a = 16
= 175.5cm2
b =11
h = 13

6. What Goes In The Box ? 3 Find the area of the shapes below : 13cm (1)
(2)
Answers

7. What Goes In The Box ? 3 Find the area of the shapes below : 13cm
(1)
20cm
13cm
10cm
165cm2
2.7m
5.4m
4.9m
(2)
19.85m2 (to 2 d.p)